/*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2016 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* limitations under the License.
*/
-#ifndef FOLLY_VARINT_H_
-#define FOLLY_VARINT_H_
+#pragma once
+#include <type_traits>
+#include <folly/Conv.h>
#include <folly/Range.h>
namespace folly {
/**
* Decode a value from a given buffer, advances data past the returned value.
*/
-uint64_t decodeVarint(ByteRange& data);
+template <class T>
+uint64_t decodeVarint(Range<T*>& data);
/**
* ZigZag encoding that maps signed integers with a small absolute value
inline uint64_t encodeZigZag(int64_t val) {
// Bit-twiddling magic stolen from the Google protocol buffer document;
// val >> 63 is an arithmetic shift because val is signed
- return static_cast<uint64_t>((val << 1) ^ (val >> 63));
+ auto uval = static_cast<uint64_t>(val);
+ return static_cast<uint64_t>((uval << 1) ^ (val >> 63));
}
inline int64_t decodeZigZag(uint64_t val) {
return p - buf;
}
-inline uint64_t decodeVarint(ByteRange& data) {
+template <class T>
+inline uint64_t decodeVarint(Range<T*>& data) {
+ static_assert(
+ std::is_same<typename std::remove_cv<T>::type, char>::value ||
+ std::is_same<typename std::remove_cv<T>::type, unsigned char>::value,
+ "Only character ranges are supported");
+
const int8_t* begin = reinterpret_cast<const int8_t*>(data.begin());
const int8_t* end = reinterpret_cast<const int8_t*>(data.end());
const int8_t* p = begin;
uint64_t val = 0;
- if (LIKELY(end - begin >= kMaxVarintLength64)) { // fast path
+ // end is always greater than or equal to begin, so this subtraction is safe
+ if (LIKELY(size_t(end - begin) >= kMaxVarintLength64)) { // fast path
int64_t b;
do {
b = *p++; val = (b & 0x7f) ; if (b >= 0) break;
b = *p++; val |= (b & 0x7f) << 49; if (b >= 0) break;
b = *p++; val |= (b & 0x7f) << 56; if (b >= 0) break;
b = *p++; val |= (b & 0x7f) << 63; if (b >= 0) break;
- throw std::invalid_argument("Invalid varint value"); // too big
+ throw std::invalid_argument("Invalid varint value. Too big.");
} while (false);
} else {
int shift = 0;
val |= static_cast<uint64_t>(*p++ & 0x7f) << shift;
shift += 7;
}
- if (p == end) throw std::invalid_argument("Invalid varint value");
+ if (p == end) {
+ throw std::invalid_argument("Invalid varint value. Too small: " +
+ folly::to<std::string>(end - begin) +
+ " bytes");
+ }
val |= static_cast<uint64_t>(*p++) << shift;
}
}
} // namespaces
-
-#endif /* FOLLY_VARINT_H_ */
-